The intent of this proposed research is to carry out stereospecific total synthesis of the following sesquiterpenes; helenalin, aromatin, confertin, eirolangin. These syntheses are all relatively brief, 20 steps or less. In principle, the final products attained are optically active in that chiral starting materials are used for each synthetic route. Additionally, these synthetic routes are designed to accommodate structural variations that may ultimately lead to enhanced biological activity. Further, these reaction pathways will accomodate radioactive labelling at certain key points in each molecule to facilitate metabolic studies.